A solar cell element, attracting attention as a clean source of energy, is required to reduce a loss in output characteristics for increased output characteristics. The causes of the loss in the output characteristics of the solar cell element include optical losses, for example, a reflection loss and a transmission loss, and electrical losses, for example, the loss of carriers due to their recombination and an ohmic loss.
Patent Document 1, for example, discloses a solar cell element equipped with a semiconductor layer, a passivation film formed on the semiconductor layer, and an electrode, wherein an oxygen-surplus region is formed between the semiconductor layer and the passivation layer, in order to inhibit (i.e., reduce) the reflection loss and the loss of carriers due to the their recombination. For this purpose, a passivation film is formed after the surface of a semiconductor is processed with a nitrogen plasma. The passivation film refers to a film which functions as a protective film for protecting the semiconductor layer, and also functions as an anti-reflection coating film.